A thin-film transistor and a capacitor are known as elements which constitute each pixel in a display device such as a television, a personal computer, a smartphone or a tablet terminal.
This type of display device is required to improve the image quality in the pixel area. In addition, it is important to reduce the electricity consumption of the semiconductor device and the active matrix substrate used for the display device.
In the above display device, when the capacitance of the capacitor has voltage dependence, the image quality in the pixel area may be degraded.